In the past week I've gone out to collect eggs and in one nest I'll find a few duck eggs (which is OK since I have ducks) and some chicken eggs but there is a substance that looks like a broken yolk on a few of the eggs. Yesterday one of my SLW was sitting in the nest and when she got out all the eggs were covered with the goo. There is no evidence of egg eating - no broken shell at all. What is it? Do I have one hen laying yolks in the nest? Or could something else be going on? Just for more info we have 20 hens and got 18 eggs today so almost everyone seems to be laying normal eggs.